1. Field Of The Invention
The field of art to which this invention pertains is that of force applying mechanisms, and more specifically, to a rigid and deformable hydraulic seal particularly adaptable for use in hydraulic brake systems.
2. Description Of The Prior Art
The prior art is replete with automatic brake adjusting and reset devices that progressively advance the retracted position of the piston to compensate for brake wear. Examples of prior art include the inventor's own prior U.S. Pat. No. 3,376,959 which discloses the use of a typical fluid motor utilizing a piston and a rubbing O-ring type seal in addition to a separate automatic brake adjuster mechanism. U.S. Pat. No. 3,403,754 to Barrett et al. again shows the use of a piston rubbing against an elastomeric seal contained in the cylinder housing. Separate bellows-type return and adjustment means are also utilized. While these prior art devices appear to perform satisfactorily in the brake environment for which they were designed, they appear to be structurally complex, costly to manufacture and sometimes difficult to service.
U.S. Pat. No. 3,851,567 to Thompson discloses a brake mechanism that includes an actuator having a pair of spaced end portions, an endless side wall extending between the end portions and at least one inelastically deformable corrugation formed in the side wall that tends to flatten out inelastically when the actuator is forced to extend and thus increase the space between the end portions. However, this thin-walled bellows-like member also utilizes a substantially rigid internal reinforcing member and a layer of elastomeric material in addition to a resilient packing ring. This structure is both structurally and functionally complex.